Geophysical Constraints on the Relationship Between Seamount Subduction, Slow Slip, and Tremor at the North Hikurangi Subduction Zone, New Zealand
Geophysical Constraints on the Relationship Between Seamount Subduction, Slow Slip, and Tremor at the North Hikurangi Subduction Zone, New Zealand
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DOI：
10.1029/2018gl080259
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发表时间：
2018-12-16
影响因子：
5.2
通讯作者：
Wallace, Laura
中科院分区：
文献类型：
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作者：
Barker, Daniel H. N.;Henrys, Stuart;Wallace, Laura
我们使用叠前深度偏移反射图像和磁异常数据在整个北方Hikurangi俯冲带，新西兰，约束板块边界结构和几何形状的俯冲海山在一个区域的浅慢滑和最近的国际海洋发现计划钻探。我们的三维模型显示，俯冲海山是一个西南-东北走向的菱形脊，长约40公里，宽约15公里，起伏可达2.5公里。这座海山大致与一个20公里宽的缺口有关，该缺口将两个大的（> 10厘米）缓慢滑动块隔开，并与2014年9月至10月吉斯伯恩缓慢滑动事件有关的构造震颤发生地有关。最大的缓慢滑动幅度发生在滑脱层下方有3.0公里厚的高反射俯冲沉积物区的地方。该带内的波速比邻近和上覆地层低7%，支持俯冲沉积物内的高流体压力可能促进沿着北希库朗吉边缘的浅缓慢滑动的观点。我们确定了俯冲太平洋板块上俯冲海山的位置和几何形状，并建立了它与发生在太平洋板块上的缓慢滑动和震颤的空间关系。2014年9月至10月的板块边界。我们推断，缓慢滑动似乎优先发生在有沉积物与高流体压力的孔隙流体俯冲附近的海山，但减少以上的海山本身。这一观察结果的影响，了解什么样的物理条件有助于空间变化的摩擦性质的板块界面，可能控制断层滑动行为的大型，板块边界俯冲推力。
We use a prestack depth migration reflection image and magnetic anomaly data across the northern Hikurangi subduction zone, New Zealand, to constrain plate boundary structure and geometry of a subducting seamount in a region of shallow slow slip and recent International Ocean Discovery Program drilling. Our 3-D model reveals the subducting seamount as a SW-NE striking, lozenge-shaped ridge approximately 40 km long and 15 km wide, with relief up to 2.5 km. This seamount broadly correlates with a 20-km-wide gap separating two patches of large (> 10 cm) slow slip and the locus of tectonic tremor associated with the September-October 2014 Gisborne slow slip event. Largest slow slip magnitudes occurred where the decollement is underlain by a 3.0-km-thick zone of highly reflective subducting sediments. Wave speeds within this zone are 7% lower than adjacent and overlying strata, supporting the view that high fluid pressures within subducting sediments may facilitate shallow slow slip along the north Hikurangi margin.Plain Language Summary Using a suite of geophysical data from the northern Hikurangi margin, New Zealand, we determine the location and geometry of a subducting seamount on the subducting Pacific Plate and establish its spatial relationship with slow slip and tremor that occurred on the plate boundary in September-October 2014. We infer that slow slip appears to occur preferentially where there are sediments with high fluid pressure in pore fluids subducting adjacent to the seamount but is reduced above the seamount itself. This observation has implications for understanding what physical conditions contribute to spatial variation in frictional properties of the plate interface that may control fault slip behavior on large, plate boundary subduction thrusts.